1. Field of the Invention
This invention relates to an automatic control method for operating an automatic control system for adjusting a final control element, which particularly consists of a rod for actuating the control rods of fuel injection units of internal combustion engines, in which method a position sensor is operated to deliver actual-position signals representing actual positions of the final control element to a computer, which is operated to compare said signals with desired-position data associated with correcting signals delivered to an actuator for moving the final control element and to detect a deviation and is also operated to correct said correcting signal so as to eliminate said deviation.
2. Description of the Prior Art
When it is desired to move the final control element to positions which correspond as exactly as possible to correcting signals, an actuator which is operatively connected to the final control element may be incorporated in a feedback control loop in which the actual position of the final control element are compared with desired-position signal depending on the correcting signal. In that case the exactness of the control will highly depend on the validity of the desired-position data, which are stored in the computer in association with electric correcting signals. The actuator will then move the final control element until the actual-position signal that is delivered by the position sensor agrees with the desired-position signal associated with the correcting signal. In the previous practice said desired-position data are stored as a result of a manual association of specific reference positions of the final control element with predetermined actual-position signals generated by the position sensor so that the automatic control system must be adjusted in a rather time-consuming and difficult adjustment. This need is inconvenient particularly when the automatic control systems have been made in series because even if they have the same basic design a general adjustment will not be sufficiently accurate so that each automatic control systems must individually be adjusted to allow for the different tolerances in the means for operatively connecting the actuator to the final control element. If it is desired to automatically control the fuel injection units of internal combustion engines, where the quantities of fuel to be injected must be exactly controlled, it will not be sufficient to ensure that the coupling elements associated with the control rods of the fuel injection pumps are exactly positioned on the common actuating rod but the position of the actuating rod and the magnitude of the signals delivered by the position sensor must properly be matched for an aquisition of the desired-position data so that the non-productive times in the manufacture of internal combustion engines will be increased as well as the manufacturing costs.